Smart Junction Box (SJB)
SMART JUNCTION BOX (SJB)
Principles of Operation
NOTE:The time out for the battery saver relay and the accessory delay relay is 1 minute if the vehicle has less than 80 km (50 miles). For additional information on the battery saver relay, see Initial Inspection and Diagnostic Overview. For additional information on the accessory delay relay, see - Description and Operation. Once the vehicle passes the approximate mileage threshold of 80 km (50 miles), the time out for both relays will be the normal 10 minute time out, as described by the Owner's Literature.
The SJB is a multifunction control module that controls many of the vehicle systems. Several SJB functions utilize hardwired inputs and/or outputs. The SJB controls the following hardwired functions, using the corresponding inputs and outputs:
In addition, the SJB is involved in other vehicle systems through communication over the controller area network (CAN). For a detailed list of SJB network inputs and outputs, see Module Configuration.Some SJB parameters are programmable. Two types of programmable parameters are available: vehicle configuration and customer preference. See Module Configuration for additional information on programmable parameters.
Field-Effect Transistor (FET) Protection
The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (voltage or ground provided by the module is turned off) when a fault is detected. A continuous DTC is stored at that time for the fault.The circuit will reset after an ignition cycle or customer demand of the function (which will switch the component on, causing the 30-minute battery saver timer to be energized). When an excessive circuit load occurs several times, the module shuts down the output until a service procedure is carried out. At the same time, the continuous DTC that was stored on the first failure will not clear by a command to clear the continuous DTCs.The module will not allow this code to be cleared or the normal circuit function restored, until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand DTCs present), the continuous DTC will have been cleared and the normal circuit function will be restored.
The SJB has three predefined levels of short circuit tolerance established. When the first or second level is reached, the continuous DTC associated with the short circuit sets along with DTC B106E. These DTCs may be cleared using the Clear DTC operation on the scan tool as long as the fault itself has been corrected. Each time the scan tool retrieves DTCs from the module while a circuit is shorted, a level of short circuit tolerance is used.If any of the circuits are shorted pas the third level (if DTCs have been retrieved 3 successive times with the short circuit not having been repaired), ten DTCs B106F and B1342 set along with the associated continuous DTC. These DTCs cannot be cleared and the module must be replaced.
The initial short circuit must be successfully repaired and its associated DTC cleared before the SJB is replace or the new SJB may experience one or more of the short circuit tolerance levels being used, causing a repeat replacement of the module.DTC B106E sets when the SJB has disabled a circuit due to a repetitive fault causing a circuit overload. A corresponding DTC for the circuit in question will also be set as follows:
- DTC B1034 - Radio Start Signal Circuit Failure
- DTC B1218 - Horn Relay Coil Circuit Short to Battery
- DTC B1304 - Accessory Delay Relay Coil Circuit Short To Battery
- DTC B1316 - Battery Saver Relay Coil Circuit Short To Ground
- DTC B1349 - Heated Backlite Relay Short To Battery
- DTC B1474 - Battery Saver Power Relay Circuit Short To Battery
- DTC B1502 - Lamp Turn Signal Left Circuit Short To Ground
- DTC B1506 - Lamp Turn Signal Right Circuit Short To Ground
- DTC B1626 - Lamp Keypad Output Short Circuit To Ground
- DTC B2070 - Trailer Tow Relay Coil(s) Circuit Failure
- DTC B2501 - LF Lamp Low Beam Circuit Failure
- DTC B2503 - RF Lamp Low Beam Circuit Failure
- DTC B2505 - LF Lamp High Beam Circuit Failure
- DTC B2507 - RF Lamp High Beam Circuit Failure
- DTC B2512 - Front Fog Lamp Relay Ckt Short to Battery
- DTC C1788 - Stoplamp Relay Output Circuit Short to Ground
- DTC C1961 - Park Lamp Relay Coil Circuit Failure
- DTC P0930 - Gear Shift Lock Solenoid Circuit Low